Process for improving cobaltmolybdenum alloys



Patented Feb. 27, 19354 TATES UNii'Eh FATE FEQE

Wei-nei- Koster, Dortmund, Germany, assignor to Vereinigte StahlwerkcAktiengesellschaft, Dusseldori, Germany No Drawing. Application March 9,1931, Serial No. 521,391. In Germany July 4, 1930 2 Claims.

This invention relates to cobalt-molybdenum alloys.

It has been ascertained by exhaustive experiments that cobalt-molybdenumalloys can be 5 hardened by a special heat treatment. If rolled or castalloys containing to 35% of molybdenum be heated to a temperature above1000 C.

and thereupon cooled with sufilcient rapidity in air or by immersion inwater or oil and finally 10 heated to temperatures between 500 to 900 C.

then the mechanical properties of the alloys will be very substantiallyincreased in relation to those prior to said heat treatment. If forexample, an alloy containing 75% of cobalt and 13 of molybdenum beheated to 1200 C.,

quenched in water and annealed for one hour at 800 C. the hardnessincreases from 165 Brinell in the untreated state to 215 Brinell. On

occasion there may be added to these improvable alloys, one or moreother elements, such as copper, aluminium, iron, nickel, chromium andmanganese in amounts up to Moreover the mechanical properties of suchalloys can be considerably improved by a suitable heat treat ment, suchas hereinbefore described.

It is to be understood that certain quantities of other metals suchas'Cu, Al, Fe, Ni, Cr, Mn,

may be combined with the binary alloys described,

such as will not injuriously affect the nature of such alloys and whichmay to some extent modify their properties and render them more suitablefor special requirements, without however affecting their ability toprecipitation hardening, depending upon the fact that the principal partof the alloys consists of cobalt and molybdenum; It. is to be understoodthat such compositions are covered by the phrase the balancesubstantially cobalt, used in the ensuing claims.

I claim: 1

1. A process for obtaining alloys of high hardness consisting in formingan alloy of 10 to 35% of molybdenum and the balance substantially cobaltand heating said alloy to a temperature above 1000 C. and below themelting point of the alloy, then rapidly cooling said alloy andsubsequently annealing it at temperatures between 500 and 900 C.

2. An alloy containing 10 to 35% of molyb- .denum and the balancesubstantially cobalt, hav- WERNER KCSSTER.

